Off-set ejector for punch dies



3,ti7,823 (EFF-SET EIlECTQR FOR PUNCH DES Paul R. Ekstrom, 1326 CiintonAve, Alameda, Calif. Filed July 7, 1158, Ser. No. 746,889 11 Claims. er.83-111) The present invention relates to devices for displacing workfrom a die preparatory to inserting a new piece of work.

Punch dies are presently used for forming openings in small flat metalparts. This part to be punched is positioned on a metal die block havin.openings corresponding to the openings which are to be formed in themetal part. Metal punches of the same size as the die openings areforced against the other side of the part to cut out and remove a slugof metal from the part to be punched.

Removal of the slug is efiected through slug ports which pass throughthe metal die and are tapered outwardly from the die opening.

The metal part is held in place in the desired relation to the dieopening by a metal gate secured to the upper surface of the die insurrounding relation to the metal part, so as to prevent sidewisemovement of the part relative to the die.

With the metal part nesting in the recess formed by the gate and thedie, it is rather difiicult to remove after the punching operation.Consequently, some type of ejecting means for pushing the part up out ofits nested position must be provided.

Such ejector means may consist of a pin passing through the die to apoint underneath the metal part. The pin is arranged to push the part upout of its nested position upon actuation of the pin, as by an aircylinder.

Usually, the air cylinder is formed within the die block concentric tothe pin opening and the air piston and pin are turned from a singlepiece of metal.

While the pin is extended by means of air pressure, furnished to theopposite side of the air piston, it is commonly retracted by the forceof gravity alone.

The described construction creates two serious problems. Firstly, thebores for the pin and piston must be concentric, and the in and pistonmust also be concentric. This creates machining problems.

Secondly, when the part is small or there are a number of openings to bepunched, the ejector pin must be positioned rather close to the dieopening. f necessity, the air piston must have a considerably largerdiameter than the ejector pin. Due to the concentricity of the pin andpiston, it is often difiicult, if not impossible to locate the ejectorpin.

The present invention contemplates an ejector means for punch dies inwhich the pin and piston may be non concentric, that is the pin andpiston may be eccentric with relation to each other.

Accordingly, it is a principal object of the present invention toprovide a punch die ejector construction in which the ejector pin ismounted on the piston for selective adjustment to any desired degree ofeccentricity.

Another object of the present invention is to provide an ejector inwhich the'ejector pin may be positioned close to the punch die openingwithout interfering with the slug passages. V i

A still further object of the present invention is to provide an ejectorwhich will operate when the die is in a position other than horizontalby reason of a positive displacement of the pin from its retracted toextended position and return.

It is additionally proposed to provide an ejector of the characterdescribed which is retracted by means of a spring, and in which theparts are proportioned to pre- Sydlih g Patented Friar. 5, 19%3 M ventfull compression of the spring, thus making for a longer life underrepeated use.

Other objects and features of advantage of my invention will becomeapparent from a consideration of the following description, and of thedrawing forming a part of this application.

in the drawing:

FIGURE 1 is a perspective view of an ejector for punch dies constructedin accordance with the present invention and shown partially incross-section to reveal internal details.

FIGURE 2 is a perspective view similar to that of FIG- URE l butillustrating a modified form of ejector.

FIGURE 3 is a cross-sectional view on an enlarged scale through the airpiston of FIGURE 2.

The ejector for a punch die of the present invention consistsessentially of a cylindrical chamber 6 formed in a die block 7 andhaving a cylindrical piston 8 mounte for axial reciprocation in thechamber 6.

An ejector pin 9 of smaller diameter is carried by the piston forreciprocating movement therewith and is slida- -bly engaged in a bore 11which is axially parallel with the chamber 6 and extends to a pointunderlying a portion of the Work 12 mounted in the die.

As here shown, the die block 7 consists of a hardened die member 13formed with die openings 14 and mounted upon a backing block 15. Thework 12 is held in position over the die opening 14 by a suitable gatemember 17 indicated by the phantom lines in FIGURES l and 2.

Outwardly tapering passages 18 extend through the die block 7 from thedie opening 14.

In accordance with the present invention, the ejector pin 9 and thepiston 8 may be eccentric to each other. This will permit the ejectorpin bore 11 to be positioned more closely to the die openings lid thanwould be possible where the pin and piston are concentric.

In the form of my invention illustrated in FIGURE 1, the piston 3 isofcup-shape, and provides an upstanding cylindrical wall 19 and a fiatinternal floor 21.

The ejector pin 9 is provided with an enlarged fiattened head 22slidable over the floor 21 to any desired degree of eccentricity.

The ejector pin 9 is biased toward its retracted position by a spring 23coiled around the pin and compressed between the head 22 and the upperend 24 of the chamber 6.

After the punching operation is completed, the ejector pin 9 is movedupwardly by the force of compressed air supplied to the lower end ofpiston 8 through a conduit 26. The spring 23 provides a positive returnof the piston and ejector pin to retracted position when the airpressure is removed from conduit 26, thus permitting the ejector to beused in any position.

As a feature of the invention, the spring 23 cannot be overstressed.This is accomplished by proportioning the Walls 19 and the spring 23 sothat the upper edge of the wall will contact the upper end 24- of thechamber 6 before the spring is fully compressed. This is important ininsuring that the spring does not break through many cycles ofoperation.

The form of ejector illustrated in FIGURE 1 is somewhat limited in thatthe ejector pin cannot be adjusted so that its edge coincides with theedge of the piston 8. Thus, the edge of the chamber 6 will always becloser to the slug opening 13 than the ejector pin will be.

Under certain conditions of use it is desirable to locate the ejectorpin at the edge of the chamber. The form of my invention illustrated inFIGURES 2 and 3 of the drawing makes such positioning possible.

In this form of the invention, the piston 8 is solid and is formed witha diametrically arranged groove 31 in its upper end. The ejector pin 9has an enlarged lower end 32 which engages in an undercut portion 33 ofthe v groove 31.

The return spring 23is compressed between the lower end 34 of a bore 36formed in the piston 8 and the upper end 24 of the chamber 6.

The spring 23 'is proportioned so that .it will not be fully compressedwhen the upper end 37- of the piston contacts the upper end 24 of thechamber 6. This will prevent over-stressing of the spring 'andigive it amuch longer life than would otherwise be obtained.

Preferably, a guide sleeve 38 is slidablyamountedin the bore 36 insurrounding relation to' the 'spring23 to keep the spring'aligne'd withthe bore 36. This assures that the spring cannot become misalignedandbroken ofi when the air pressure is applied to the piston.

In adapting the ejector of the present-invention to a punch die, the dieopening 14 and slug passages 18 are machined in the die block. Thechamber 6 is then bored in the backing block and the conduit 26installed.

The bore 11 for the ejector pinjis then formed in the die face in asuitable position, it being noted that 'it is only necessary for thedie' bore to open through the upper end 24 of the chamberfi at anyposition relative to the axis of the chamber.

With. this construction, no. attempt need be madeto make the bore 11concentric with the chamber 6, the adjustable feature of the ejector pinon the piston 8-automatically accommodating to. whatever eccentricity isencountered. i

Fromthe foregoing, it .will be apparentthatI have provided anv ejectorfor punch dies which is simple to machine'and to install and which isself-accommodating to various degrees of eccentricity between the pistonand the ejector pin.

I .claim:

1. An ejector for a punch. die, having a slug opening therethrough,comprising a cylindrical chamber formed in said die-in laterally spacedrelation to the slug opening, a bore of reduced, diameter formed in saiddie and hav-' ing an axis in parallel spaced relationto the axis of saidchamber and opening to said chamber and to a point underlying a portionof the work to be mounted in said die, a cylindrical piston mounted foraxial reciprocation in said chamber toward and away from said bore, anejector pin carried by: said piston for reciprocating movement therewithand slidably engaged in s'aid bor e; and means mounting the pin withrespect to the cy'linder to provide lateral movement of the pin relativeto the piston, conduit. means in said die adapted for selectivelyconnecting a sourcehof .fluid under pressure to said chamber for urgingsaid piston toward said bore whereby said pin will eject the work fromsaid die, and means eifeetive on releaseof the actuating pressure to"cause". retrograde rnovementof the ejector unit.

2. An ejector for. a punch die as described in claim 1 wherein said pinis floatingly mounted on said. piston for displacement radially thereofso as to adapt the pin and piston to chambers'and bores positioned 'with'ditferent degrees of relative eccentricity.

3. ,An ejector unit as defined in claim 1 wherein said piston is of cupshape providing? a flatinte'rnal mamas said ejector pin is formed.withauenlarge'd flattenedfhead slidable over said floor. i M

4.,An ejevcllorrunit as defined in claim 3 wherein said retrogradecausing means comprises .a"coil spring iicit cling said ejector -'.pin'iandproportionedfforbearing against said flattened head and the end ofsaid chamber adjacent said borey 5. An ejector unit ,for dies-having. acylindricalchamher and an eccentric ejector bore, comprising acylindrical piston formed for reciprocation insaid chamber, said pistonhaving an end formed with a transverse undercut slot, an ejector pinhaving a shoe portion at one end formed for sliding engagement in saidslot and having its opposite endformed forsliding engagement in saidbore, and spring means on said piston for urging the latter to retractedposition in said chamber,

6. An ejector unit as definedin claim 5 wherein said spring meansincludes a helical spring mounted in a bore in said piston forcompression between thebottom of said. bore and theconfrontingend.of-saidchamber.

7. An ejector unit as defined in claim 6 wherein'said spring isproportioned sothat it will be less than fully compressedwhen saidpistonengages .the end of said chamber.

8. An ejector unit as defined in claim- 7 wherein a tubular member isslidably mountedjin said bore in said piston, and in surroundingrelationto said-spring soas to provide a guidefor retaining -said springconcentric to said bore in said piston.

9. In a punch.die-machine, a die block formed with a punch hole adaptedto cooperate with-a punchmember and an outwardly taperedslug openingextending from said punchhole through-said die blockgrsaid die blockbeing formedwith a cylindrical chamberadapted for selective connectionto.a sourceof fluid under pressure and an. ejector bore of. smallerdiameter than said chamber and having an axis parallel to and-spaeedfroni the axis of said cylindrical chamber -wherebysaid bore maybeformed inclose proximity -to said punch hole without interference.between. said chamber 'andsaid slug opening, a cylindrical pistonmounted for axial reciprocation in said chamber and having an end'facingsaidbore formedwith ,a transverseundercut slot,-an eject'or pin axiallyre:

ciprocable insaid ejector bore and havinga shoe portion at one .endformed for sliding engagement in said slot whereby said ejector pin maybe positioned with any de sired degree ofieccentricit y to said piston,and'sprihg means compressed between said piston and the'end of saidchamber, said spring meansbeingresiliently compressible.,to,a1lo,w said.piston rise in said chamber when fluid under; pressure. isadmittedthereto and being sufiicientlystrong to retract said pistoninsaid chamber when the fluid under pressure is released from the chamber.

10. A punch die machine as 'defined in claim 9 whe1'ein ,saidpistontisnformed with an axially parallel cylingf drical recess, andsaid'spring means includes a helical spring mounted .in said cylindricalrecess and extending therefrom to bearfagainst theend of saidcham bercontainingsaidejector bore 1l.:,A punch die. machineas defined inv claim10 wherein :a .tubular. member is slidably mounted in said cylindricalrecessin said piston and in surrounding relation to said spring so as toprovide a guide for retaining said spring. in alignment with'saidcylindrical recess, said spring being proportioned so that itwill belessthan fully compressed.when said piston engages theend ofsaid chamber tolimit the stroke of said "ejector References. Cited .in' the fileofthis-patent

1. AN EJECTOR FOR A PUNCH DIE HAVING A SLUG OPENING THERETHROUGH,COMPRISING A CYLINDRICAL CHAMBER FORMED IN SAID DIE IN LATERALLY SPACEDRELATION TO THE SLUG OPENING, A BORE OF REDUCED DIAMETER FORMED IN SAIDDIE AND HAVING AN AXIS IN PARALLEL SPACED RELATION TO THE AXIS OF SAIDCHAMBER AND OPENING TO SAID CHAMBER AND TO A POINT UNDERLYING A PORTIONOF THE WORK TO BE MOUNTED IN SAID DIE, A CYLINDRICAL PISTON MOUNTED FORAXIAL RECIPROCATION IN SAID CHAMBER TOWARD AND AWAY FROM SAID BORE, ANEJECTOR PIN CARRIED BY SAID PISTON FOR RECIPROCATING MOVE-